Catalytic conversion of hydrocarbons



Feb. 13, 1951 N'. ANDERSON CATALYTIC NVERSION 0F HYDROCARBONS Filed sept. 29, 1945 Patented Feb. 13, 1951 CATALYTIC CONVERSION OF HYDRO- CARBON S Nils K. Anderson, Elmhurst, Ill.,assignor to Universal Oil Products Company, Chicago, Ill., a

corporation of Delaware Application September 29, 1945, Serial No. 619,408

3 Claims.

This invention relates to an improved process and apparatus for the catalytic conversion of hydrocarbons wherein a iiuidized finely divided catalyst is employed in a continuous conversion process. More specifically, the invention is directed to improvements in the means and apparatus for stripping' catalyst particles of occluded and adsorbed volatile hydrocarbons prior to regeneration; the improvements providing more eiiicient stripping and at the same time allowing more flexibility in the operation of the conversion unit.

The improved apparatus has an elongated stripping zone provided Within or at least partially within the reaction chamber, such that the upper portion of the stripping zone extends parallel to and is communicative with the reaction zone. The partitioning means between the conversion zone and stripping zone is provided with slots or perforations spaced throughout its height Within the conversion zone, such that the height of the catalyst dense phase may be varied without alecting the withdrawal of the spent catalyst into the stripping zone.

In the uidized type of catalytic conversion unit, a dense bed of subdivided solid catalyst is maintained Within a reaction Zone in a state of hindered settling by a continuous stream of Vaporous or gaseous reactants in order to eiliciently contact the catalyst particles. A stream of contaminated catalyst particles, upon which deleterious heavy carbonaceous products are deposited, is continuously Withdrawn from the fluid bed in the reaction Zone to a regenerating zone wherein the contaminants are removed to .2

restore the catalytic activity of the particles. The particles in the regenerating zone are maintained in a fiuidized state of hindered settling by a continuous stream of oxidizing gas which effects burning and removal of the deleterious car bonaceous material on the particles. In the truly fluidized operations, the rate of now of the reactants or of the oxidizing gas stream must be rapid enough to obtain good Contact with the catalyst particles and maintain them in a constant state of hindered settling. However, in the normal operation of the unit, above the dense phase beds in the reaction and regeneration zones, a light phase region exists in which there is little or no hindered settling and there is a substantially lower concentration of catalyst particles. .From the light phase region Within the reaction zone, the reaction products may be separated from the catalyst particles and discharged to a frac tionation system or other treating equipment.

From the light phase region Within the regeneration zone, the combustion products and flue gases may be separated from the catalyst particles and be discharged directly to the atmosphere or they may first be sent through suitable heat recovery apparatus.

Catalyst particles which are withdrawn from the reaction zone are, of course, suspended in hydrocarbon gases or vapors until a gaseous stripping medium displaces it. It is very beneficial to displace the hydrocarbons as Well as oocluded volatile material on the catalyst particles in order to decrease the load on the regeneration system and aid inthe control and the elimination of excessive temperatures during the regeneration process. The stripping medium may be steam, iiue das, or other relatively inert noncombustible gaseous material Which can be mixed With the reaction products Without adversely aiecting the quality of the products or which can be easily separated therefrom. The contaminated catalyst from the reaction or conversion zone is normally removed in a downwardly moving column and a stripping medium injected at the lower end of the catalyst column in order to pass counter-current to the descending catalyst particles. The stripping medium and the displaced hydrocarbon vapors and volatile material will then be carried upwardly to the upper region of the con- Version zone to commingle with the conversion products and be discharged from the chamber therewith, to the fractionation or other treating equipment.

One of the important features of this invention resides in providing a slotted or perforated means to separate the stripping Zone and the reaction zone, such that improved iiexible operation Within the reaction zone is made possible.

It is also an object of the invention to provide a compactly arranged fluidized catalytic conversion unit, that combines the reaction and regeneration zones Within one chamber or shell thereby eliminating much of the transfer piping and entirely enclosing a stripping zone between the reaction and regeneration sections of the unit.

A still further feature of the invention resides in providing an improved continuous flow and method of handling fine subdivided catalyst and vaporous material through an Vimproved compact arrangement of zones for the fiuidized conversion of hydrocarbons.

In the compact'uidized conversion unit provided by this invention, the reaction zone is placed above the regeneration zone within asingle vertizone. Suitable grids or perforatediiplates maybe"y spaced within this reaction zone to effect good contact between the hydrocarbon charge and .the catalyst particles throughoutthe entireheight of the dense phase bed. In the upper portion )of the reaction zone witlfin the light phase region,

. a :suitable centrifugal orV cyclone f type fseparator fmay be lplaced 'f .to i effect aiseparation: of f .catalyst *particles from .theV reaction :products: which.y are --discharged from athe'ifchamber. PAI :long ver-tical partition plate or.. a .-pipe, -fhaving.slottedorfspaced perforations, is provided to form adjoiningland `:parallel reaction and strippingizones, :and vpermit v.af-varying height densephasebed with-in the con- 4.version zone. .The withdrawal of spent 'catalyst .particles from :the reactionfzone can be made -laterally: through thel slotsf vor lopenings r .directly 1in-to the adjacent stripping* section; *wherein the .particles may -be-passed downwardly through the zone countercurrent to` afstr-ipping med-rum which :enters-the `lower endsofY the-stripping zone orl transfer conduit. Asf has previously' been. noted,

vthe stripping medium-.may .-be. steam, ueV gas,

or other 'inert4 fluid material. vIrrthe. combined unit -of this inventiongthezused for. spent. catalyst after passing through the strippingzone is-*pa-ssed directly to .the upper. level oflthedense `phase bed ``which. is t maintainedl within the regeneration zone Af substantially ."countercurrently flowing stream of -a-ir-orother oxidizinggas; is maintained f' in the regeneration--section to yiluidize -'and .reactivate the `.catalyst particles. Ai-iitable distri- `-bution plates or gridsmay-also -be placedat spaced v.levels-within this regeneration zone .to effect a uniform burning,` toaid .inlthe redistribution vof the catalyst` 'andi result ineanefcient Aregenera-V tion .of Y thev contaminatedV catalyst particles. .regenerated catalyst particles..-1^are withdrawn The from the lower portion of the regeneration-:sec-

tion...-.andT are .-passedethroughlsuitable'. conduits -and...flowcontrol= means, which-are positioned outside the: wall of the chamber, to becomemixed with the hydrocarbon-lchargeland reenter the reaction Zone. .--In-.-.the.upperfportion of the re Y.generation.-sectionfwithin.theFlight phase region, a suitable` centrifugal or cyclonetypeof.- separator 1 may also be placedto effect removal of substanr tially-.allaof they catalyst particles from the flue fgasistrearn which isV discharged from `fthe :cha-myben A .portion ofthe .outgoing-flue.gas-fstream may be -.charge.d 'tothe-lower. end-of the stripping zone to be used as the stripping medium therein.

.-fAlso, -if..desired;V .this A:por1'.i;1n..of.fluegas'sused for .stripping .may .be `Y.suitably ywashed ...orf scrubbed `.prior vtoits .use through the stripping` zone.

.A very. considerable advantage :is obtained by .placingslots or-perforationslinithe partition .plate throughout its height in.,thereaction section, as

.the operating...depth -of1 theadensevi phase bed of L catalyst.,V and -.vapor,-imay thengbe :readily vvaried xtc..any-rlesired` height, `rfandegspent. :catalystfstill permitted to be withdrawn into the stripping zone and transfer line to the regenerator. For example, with fresh catalyst particles having a high activity it may be necessary to maintain only a vvery low or shallow dense phase bed of catalyst and vapor in the reactor to obtain adequate conversion. With ea relatively .inactive:=catalyst it may be necessary to maintain-a ibedeof .considerable depth within the reactor to obtain proper residence or contact time for the required conversion, assuming of course, in each instance,

that the hydrocarbon charge is fixed or substantially constant. It is not new to have a stripping @Zonen-built'.partiallywithin the reactor chamber .andeXteriding-,intofthe conversion zone; however,

with a* ixednonperforated partition plate it is v,necessary .that thecatalyst be withdrawn down into the withdrawal and stripping zone, and

therefore any operating changes in the level of famV end roi .A the: combination chamber. catalyst-from the reaction zone can-.bewpassed -V-directly through :an-.intermediate strippingzone the dense phase bed must be made above the ltop extremity of a solid non-perforated.partition plate. This-.means-that more vertical spacefor 'a'higher reaction'zone is necessary.. Also,`| Withfa ixedheight for'ran .internally placed: stripping zone, there-may be considerable lay-passing` of ,relatively unspent catalyst into the. stripping zonefl particularly` when the `reactor-is in operation maintaining a high level. for the dense phase ybed-and the topend ofthe strippingfzone istsome distance below the .top level of the bed.A Itis-.al-

ways preferable .tov withdraw catalyst fromfthe upper portion of the dense phase bed-where .the Vcatalfysipis `likely to have the greatest amounts of carbonaceous material and occluded. `mattera-adsorbed thereon andfthis'isvmade possible-*fwith the improved ,-elongatedstripping -vsectionfprovidedby this invention.

.-.-l\/lany :advantagesarev also fou-nd in the im- Eproved-luidized operationw-hich is made possible by 1 placing the reaction -section.directly. above the regeneration section 'within a singlechamber. Theheating up of the unit` .prior to placing *it intooperation ismade. rn-uch.easier, `as .the air heater which furnishes Vthe warming up-airf-may beY placed directlybelowor adjacent .the lower .The spent and through a drop pipe-to the upper level offthe dense phase bed in theregeneration-zonefthere- .by easily attaining countercurrent flow linthe regeneration Section5.y between the 'catalystnparticles and an oxidizing-gas streamf which-may VVente-r the lower end of the vregeneration zone.

With..countercurrent vflow of the spentcatalyst .and airinthe regeneration zone, it is possible .to

iutilize the upperportion of'this.- zone asa-*secondary stripping sectiom for the operation with- Y in.. the regeneratingzone-may be controlledso that thegasesat the top ofv the dense phase bed .are .substantially yflue-and -combustion -gases which have very little or no 'oxygen' present. Thus, `the'inert vflue gas mayfbe employedfto t function asf-asecondary stripping medium at the upperV level .-of the bedwhere theispentlcatalyst eceived from the*reactionozonefand the. pristrippingrzone above. Also as'may benoted a connection `with Y -thefaccompa'nyingdrawing,

l. a flue gas stream'fromthe regeneration' Zonemay be :eadily used to function as the strippingainedium in tlleprimary' stripping-Zone whichwill -bezdirectly above the 1 regeneration' zone.

Still other'advantages are realized-.inthe compact arrangement, such -zas eliminating: aA major portion .of the '.catalysttransfer: lines. '.:TIhisLnot -cf the unit possible.

only lowers the cost of the unit by saving piping, insulating material, expansion joints, etc. but it also eliminates much loss of heat from the unit.

Still other advantages will be apparent from the accompanying drawing and the description thereof.

Figure 1 shows a compact improved fluid catalyst conversion unit, with the reaction section superimposed above the regeneration section.

Figure 2 shows a sectional plan view through the upper portion of the unit shown in Figure l as indicated by line 2 2.

Figure 3 shows an elevational view of a reactor chamber, where the stripping zone is partially within the chamber adjacent the reaction zone, and a slotted partitionplate is used to separate the two zones.

Referring now to Figure l of the drawing a hydrocarbon and catalyst contacting Zone or reaction zone i is placed alzi-ove a catalyst regeneration zone 2 within a single vertically placed chamber 3. rl-"he fluid charge and the finely divided catalyst particles are carried to the re action zone by way of conduit the regenerated catalyst particles being withdrawn from the regeneration Zone through the conduit 5 and fed into the conduit ll. The valve ii is placed in the line 5 to provide control for the flow of the regenerated catalyst. The reactants and catalyst are charged to the lower end of the reaction zone i at a point just above a separation plate i which is placed across the chamber. Substantially horizontal distributing grids or perforated plates are positioned at spaced points within the reaction zone i, and serve to aid in the contact required between the reactants and catalyst particles.

Spent and contaminated catalyst is passed from the conversion zone l into the adjacent well or strippingr Zone 9 and caused to ilow downwardly through this stripping section to the re generation zone 2 below. Relatively open grids or perforated plates Ei! are spaced within this stripping zone 9 to effect redistribution and goed contact between the catalyst particles and the countercurrently flowing stripping medium which enters the lower end of the stripping zone. Control of catalyst flow through the pipe i i and stripping zone 9 is maintained by the valve I2 which has an extended stem and control wheel I3 carryinlg to a point exterior of the chamber wall 3.

The partition plate Hl, between the stripping zone 9 and reaction zone i within the upper section of the chamber, is provided with slots i5. Thus, spent catalyst may be allowed to pass laterally into the well and stripping zone Q, even though the top level of the dense bed, indicated by the broken line E, is below the top of partitioning plate i6. The spaced slots l5 permit a varying height of the dense phase bed in the reaction zone and thus comprise a valuable improvement, making a more ilexible operation In the modification shown in Figures l and 2, the catalyst beds in the reaction and stripping zones extend to near the uppermost slots i5, with the bed in the reaction zone being slightly higher than the bed in the stripping zone. Also, the flow of stripping me" diuin is controlled to obtain a greater density of catalyst particles in the stripping zoney than in the reaction zone. As a result, catalyst particles are transferred from the reaction zone to the stripping zone only through the uppermost slots l5.

Within the upper portion of the reaction zone 6 I above the normal top level of the dense phase bed a cyclone type of separator il is indicated which serves to separate the catalyst particles from the reaction products. The reaction products are discharged from the vessel by way of outlet i8 to suitable fractionating and treating equipment, which is not illustrated, while the Aseparated catalyst particles are returned to the dense phase portion of the zone through a suitable return pipe E. `The valve 2S with the extended handle is operative to control the return ilow of the separated catalyst particles to the contacting zone within the dense phase bed.

Within the regeneration zone 2, the contaminated catalyst particles, which are discharged thereto from the drop pipe i l, are contacted in a fluidized bed with an oxygen containing stream to eiect burning of the contaminants thereon and thus regenerate the catalyst. The oxygen containing stream or air is charged to the lower portion of the regeneration Zone 2 by way of conduit 2| and passes through a perforated plate 22 to contact the catalyst particles in a dense phase bed in which the catalyst is maintained in a state of hindered settling. Additional perforated plates or grids 23 are placed across the regeneration zone 2 and serve to act as redistribution grids for the catalyst and air streams as well as serve to divide the zone into vertical stages of regeneration. The plates 23 will, of course, have a substantially greater per cent of openings than the lower plate 22 which passes the upwardly moving lair stream only. Withdrawal of regenerated catalyst is made from this zone 2 as indicated by way of conduit 5 which joins the charge conduit t.

ln the upper portion of the regeneration zone 2 above the top oi the normal dense phase level, which is indicated by the broken line 2li, a seoond cyclone type of separator 25 is positioned. rlhis separator 25 serves to separate the catalyst particles from the combustion gases or flue gas stream and return the particles to the dense phase bed within the regeneration zone 2. The valve 26, with the handle extended to a point exterior of the chamber' wall il and positioned at the lower end of separator unit 25, serves to control the return flow of the separated catalyst particles. rlhe nue gas stream from the separator 25 is discharged from the chamber by way of outlet 2l, from which it may be carried to a stack or to suitable heat recovery equipment, such as a waste heat boiler or the like,

` (not shown) A portion of the flue gas stream from the regeneration Zone may conveniently serve as a stripping medium, in the flow arrangement of the compact unit shown, a line gas stream is withdrawn through conduit 2&2 and passed through a small compressor 29 which charges the stream at 'a suitable rate and pressure through conduit 28 to the lower end of the strip- Iping zone 9 to pass upwardly therethrough aan: rase T7 yinthegeggrids.`I- I within .z .the 'stripping section :may Vloe grating, perforated plate, vor the"..like,1or.f.of :course:conventional types` of contactrtrays and decks i may' be employed.

. In Figure 3 of theV draw-ingzareactor chamber -f3f.is-shown whichds'maintained separate from the regenerator chamber. :A slightly different f form' of apparatuszisashown. in" thisview,` as com- .p'ared to that'i'llustrated'in the compact form .of the entireSiiu-idized'unit or-*Figure 1. The;

chamber Silhousesthe reaction zone` 3I` and the -upper portion 'of-a stripping Zone r32- whichpartiallyfexten'ds celowrthe reactorzone -illY into a Y.smaller cylindrical :chamber A:33. Thef-partition :,.plate-v34, between' the reaction zone-l..:and.nthe x15 upper Iwithdrawal sectionx-of thestripping Y zone, .-is provided with vertically:A spaced -slots'f35. As .f in-v theicha-mber Vof VFigure 1, the slots in. theffpartitionv plate provide foiv van* :improved method of Ireceiving 'spent catalystn and :stripping Vits:y effi-w20 ".ciently in 4an elongated `Zonewith a countercurrently -fflowing i gaseous f medium. '.Theestrip- .--ping gas mayhe chargedlthrough 4line-35 at the "lower end` of the lzone 32,i-the ratewotflowvbeing .f'controlled by valve ilpwh-ile catalyst:particlespV substantially Y stripped of contaminating v-and .-.Volatile material, may "be discharged through -concluit Blaat the lower end ofthe strippingzone. :In yoperation the vaporized t hydrocarbon c charge -andinelydivided catalyst particles'areA =carried `by wayof the inlet-conduit-to the lower fend of the-reaction zone 3|; 'at a' suitablestemlperature for conversion. The :mixture is passed .throughf al distributingfgridor.; perforated plate v 39 and is maintained in adense:phasefleedgtlfieY ,from thezupper portion: of the-dense 'phase "bed through the slots '35 into the stripping zonez-SZ. .By-.maintaining a lower 'velocitywstripping gas stream; as compared tothe rate-ot :flowin thereaction zone, the travel of catalyst. particles-will always be principallyfrom' the 'upper portion of -the bed into the stripping zone 32,"regardlessof theheight of thedense phase bed'ysince the Alower v relativefvelocity will result in a 'moredense. catalyst phase within thisfzoneSZ. .The higher-idenfsity-c'atalyst column in the stripping zone' 32.pre

`ventsany lay-passing of catalystfintothe lower A.slots :35 from 1 the lower portion "of ythefdense -1phase hed. While there may loe-some outwardcir- .cnlation of catalyst fromthenstrippingzonefZ 1i-nto the reaction zonet l it will-be .veryslightfand :not be detrimental in anysrespectrtoathe conversion process :taking place. The 'strippingzvmedium entering line SS as zpreviouslyiv noted may tbe steam, ue gas, Vor any suitable inerti gaseous :.inedium. Y

A great amount of iiexibility Vzin; the 'operation .of/the reaction chamber is attainedbythe irnproved method' of withdrawing'lspent,catalyst t from the reaction .zonelthrough 'the' slots into :the elongatedzstrppng zone. :.Anyheightaof .75:

dense? phasefbedz-may'be' maintainedeasfre'qui-red .the-:activity .of .f the :catalyst'ior i the`V residence time desired? .fori-1 contacting :the 'catalyst `,and

vaporxrnixture. 'In addition; amore uniform 'istrippingfioperation andv amore .uniformi conversion of the reactants is obtained by this improved 'apparatus arrdzmetho'd vof?,operation.

inloperating ltheiunitary and vvimproved apparatus of l Figure 1 several advantages.r are attained.

iIhefizc'atalyst travellf ist greatly'. decreased, with :conduits `.necessary 'onlyitol transfer' the regenerated catalyst from the-regeneration'section `2 to the .'reaction section i. l*The spenti-catalyst from'.'the-rreaction `zone! travelsentirely within the eh'amber'wall 3;fbeing'transferred tlfi'roughthe liinproved stripping'-zone 53 downwardly' :to-the regeneration zone 2. In this unit, -iineigas is utilized to "pass upward 'countercurrently tolthe "spent catalyst :inl thestripping :zone 9 and'V to eifectdisplaceinentfof hydrocarbon vapors or-other Volatile'matter 'being-entrainedwith the'catalyst.

Also aspreviously-mentioned, flue gas at thetop of the dense phase bed above" the upper distribuftion. plate 34 may employed to Yact as av-stripping` frne'diurn :in-atsecondarylstripping operation,

` within? the regeneration zone.

'Themaj'or portionfofk the flue gas'from the regeneration section 'ofcourse Ypasses' through the separator-25 `and is ldischargedfrom the unit. The separated catalyst 'particles from'the'fseparator`25 and the stripped spent catalyst particles from the reaction zone l are charged to the upper portion of the fluidized'bed', ywith the oxidizing air v stream charged -to the lower end of the zone through conduitfZi.` 'The elevated reaction' Zone I makes this desirable 'counterc-urrentiiowwithin the regenerator section very easily=lattainable "This ilow is of advantage; resultingV in very effifcient regeneration and in addition decreases the 40 chances of 'excessive' temperatures andfafterburn- 'ing' in the light phase region of the regenerating 'zone 52. Since fthe catalyst withthe `greatest amount vof carbonaceous matter and 'entrained oxidizable ymaterial is'brought into the upper part 1i.;V of thefzonewhere vthe least alnount'of oxygen is zniaybe of various conventional types. entation'andthe-'shape'of the stripping zone may vary; also', 'the placing o f the slots'or openings present'fin the gas, `wliile catalyst with the least Yamount 'of contaminating material ispresentl'in the lower: portion ofthe zone above vthe gridi. where the air or oxidizing gas 'stream rst'enters the catalyst 'bed and is high in oxygen content.

In thespecic vforms fofthe apparatus shown and described it is obvious variousI changes or substitutions inaybe made in their construction.

For instance, 'no invention-would be involved Jin using 'different'types of catalyst separators-'or in using dilierentv grids -or distributing plates-which The voriinl the` partitioning 'means within lthe reaction Zone' may beva'ried' somewhat asirnay be -notedfin Y i the'changing fof their positionsl in Figures 1` :and

fconve'rsion process; iasfit .may be` usediior the `catalytic -cracki-ngf of hydrocarbonaz catalytic de-V hy'dr'ogenation,.y catalytic@ ar'o'matiaation4 Ior other lasimilar.'"fluidized processes.

3 of f the drawing.

'The improved method-of theliowland` apparatus fthis invention is not-limited to anyone Iclaimas my. invention: Y

15in afprocessy fori the Vconversion of fluid reactants inthe presence of'. subdivided .solid catalystzp'articles' wherein'the reactants are `contacted at conversion conditions with catalyst .particles ini.axreactien,aoneaandtheireaction :products are separated from said catalyst particles and discharged from the reaction zone, the improvement which comprises passing contaminated catalyst particles from the reaction zone laterally through a partition having vertically spaced openings into an adjoining stripping zone, passing a iluid stripping medium upward through said stripping zone, controlling the flow of said stripping medium to obtain a greater density of catalyst particles in said stripping zone than in said reaction zone, maintaining said contaminated particles in the stripping zone as a dense fluid bed extending to an elevation adjacent an open portion of said partition, maintaining the catalyst particles in the reaction zone as a dense iiuid bed extending to a slightly higher elevation than said bed in the stripping zone but below the top ci said partition, transferring catalyst particles from the reaction zone to the stripping zone only from said higher elevation in the reaction Zone to said elevation in the stripping zone through said open portion of the partition, passing the stripping medium and stripped volatile matter from the upper portion of said stripping zone to the upper end of said reaction zone to be discharged thereirom with said reaction products and discharging stripped contaminated catalyst particles from the lower end of said stripping zone for regeneration.

2. In a process for the conversion of fluid reactants in the presence of subdivided solid catalyst particles wherein the reactants are contacted at conversion conditions, said catalyst particles being maintained in a uidized state in a reaction zone, the reaction products are separated from said catalyst particles and discharged from the reaction zone, contacted catalyst particles are passed from said reaction zone to a regeneration zone wherein said catalyst particles are maintained in a fluidized state and reactivated by a gaseous oxygen containing stream, the improvements which comprise passing a mixture of reactants and catalyst to the lower end of said reaction zone, passing contaminated luiclized particles from said reaction zone laterally through a partition having vertically spaced openings to an adjacent stripping zone, passing a uid stripping medium upward through said stripping zone, controlling ow of said stripping medium to maintain a greater density of catalyst particles within said stripping zone than in said reaction zone and to allow the downward travel of said catalyst particles, maintaining said contaminated particles in the stripping zone as a dense fluid bed extending to an elevation adjacent an open portion of said partition, maintaining the catalyst particles in the reaction zone as a dense fluid bed extending to a slightly higher elevation than said bed in the stripping zone but below the top of said partition, transferring catalyst particles from the reaction zone to the stripping zone only from said higher elevation in the reaction zone to said elevation in the stripping zone through said open portion of the partition, passing said stripping medium and stripped volatile material from the upper portion of said stripping zone to the upper end of said reaction zone to be discharged thereirom with said reaction products, discharging stripped contaminated catalyst particles from the lower end of said stripping zone to the upper portion of said regeneration zone,

effecting iiuidized contact between said contaminated catalyst particles and said oxygen containing gas stream in said regeneration zone. withdrawing reactivated catalyst from the lower portion or last said zone and returning it for reuse to said reaction zone and discharging nue gases from the upper portion of said regeneration zone.

3. In a process for the conversion of iiuid reactants in the presence of subdivided solid catalyst particles wherein the reactants are contacted at conversion conditions, said catalyst particles being maintained in a fluidized state in a reaction zone, the reaction products are separated from said catalyst particles and discharged from the reaction zone, contacted catalyst particles are passed from said reaction zone to a regeneration zone wherein said catalyst particles are maintained in a fluidized state and reactivated by a gaseous oxygen containing stream, the improvements which comprise passing a mixture of reactants and catalyst to the lower end of said reaction zone, passing contaminated fluidized particles from said reaction zone laterally through a partition having vertically spaced openings to an adjacent stripping zone, passing a stripping medium of iiue gas upward through said stripping zone descending therein, controlling the upward iiow of said flue gas to maintain a greater density of catalyst particles within said stripping zone than in said reaction zone and to allow the downward travel of said catalyst particles, maintaining said contaminated particles in the stripping zone as a dense fluid bed extending to an elevation adjacent an open portion of said partition, maintaining the catalyst particles in the reaction zone as a dense iiuid bed extending to a slightly higher elevation than said bed in the stripping zone but below the top of said partition, transferring catalyst particles from the reaction zone to the stripping zone only from said higher elevation in the reaction zone to said elevation in the stripping zone through said open portion of the partition, passing said iiue gas stripping medium and stripped volatile material from the upper portion of said stripping zone to the upper end of said reaction zone to be discharged therefrom with said, reaction products, discharging the stripped contaminated catalyst particles from the lower end of said stripping zone to the upper portion of said regeneration zone, effecting nuidized contact between said contaminated catalyst particles and said oxygen containing stream in said regeneration zone, withdrawing reactivated catalyst from the lower portion of said regeneration zone and returning it for reuse to said reaction zone and discharging ue and combustion gases from the upper portion of said regeneration zone.

NILS K. ANDERSON.

REFERENCES CITED The following references are of record in the ille of this patent:

UNITED STATES PATENTS Number Name Date 1,873,783 Osterstrom et al. Aug. 23, 1932 2,341,193 Scheineman Feb. 8, 1944 2,378,542 Edmister June 19, 1945 2,414,852 Burnside et al Jan. 28, 1947 

1. IN A PROCESS FOR THE CONVERSION OF FLUID REACTANTS IN THE PRESENCE OF SUBDIVIDED SOLID CATALYST PARTICLES WHEREIN THE REACTANTS ARE CONTACTED AT CONVERSION CONDITIONS WITH CATALYST PARTICLES IN A REACTION ZONE AND THE REACTION PRODUCTS ARE SEPARATED FROM SAID CATALYST PARTICLES AND DISCHARGED FROM THE REACTION ZONE, THE IMPROVEMENT WHICH COMPRISES PASSING CONTAMINATED CATALYST PARTICLES FROM THE REACTION ZONE LATERALLY THROUGH A PARTITION HAVING VERTICALLY SPACED OPENINGS INTO AN ADJOINING STRIPPING ZONE, PASSING A FLUID STRIPPING MEDIUM UPWARD THROUGH SAID STRIPPING ZONE, ZONE, CONTROLLING THE FLOW OF SAID STRIPPING MEDIUM TO OBTAIN A GREATER DENSITY OF CATALYST PARTICLES IN SAID STRIPPING ZONE THAN IN SAID REACTION ZONE, MAINTAINING SAID CONTAMINATED PARTICLES IN THE STRIPPING ZONE AS A DENSE FLUID BED EXTENDING TO AN ELEVATION ADJACENT AN OPEN PORTION OF SAID PARTITION, MAINTAINING THE CATALYST PARTICLES IN THE REACTION ZONE AS A DENSE FLUID BED EXTENDING TO A SLIGHTLY HIGHER ELEVATION THAN SAID BED IN THE STRIPPING ZONE BUT BELOW THE TOP OF SAID PARTITION, TRANSFERRING CATALYST PARTICLES FROM THE REACTION ZONE TO THE STRIPPING ZONE ONLY FROM SAID HIGHER ELEVATION IN THE REACTION ZONE TO SAID ELEVATION IN THE STRIPPING ZONE THROUGH SAID OPEN PORTION OF THE PARTITION, PASSING THE STRIPPING MEDIUM AND STRIPPED VOLATILE MATTER FROM THE UPPER PORTION OF SAID STRIPPING ZONE TO THE UPPER END OF SAID REACTION ZONE TO BE DISCHARGED THEREFROM WITH SAID REACTION PRODUCTS AND DISCHARGING STRIPPED CONTAMINATED CATALYST PARTICLES FROM THE LOWER END OF SAID STRIPPING ZONE FOR REGENERATION. 